Research on Design of DC Filter Systems of Multiterminal DC Transmission Systems

The suppression effect of DC filter systems on DC harmonics affects the communication line, DC systems insulation level and DC side resonance. Multi-terminal DC transmission systems are more complicated than two-terminal DC transmission systems in the design of DC filter systems. In this paper, the DC filter of all converter stations are combined to form a DC filter system, and the system is optimized. This paper analyzes the complexity of the design of DC filter systems of multi-terminal DC transmission systems. The performance design of DC filter is introduced. The influence of the operating state of the DC filter of each station on the harmonics of different DC lines is analyzed, and the distribution law and influencing factors of the harmonics of the DC line are obtained. By adjusting the configuration scheme of the DC filter and the capacitance value of the DC filter high voltage capacitor, etc., the principles for optimizing the DC filter systems is proposed. The simulation results of the 3-terminal systems are used to verify the effectiveness of the proposed method.